/

This search engine is so powerful that basically all the questions you want will be answered.

/

This is relatively simple and easy to use.

Physics:

/

Well-known foreign mathematical forums are more efficient than Baidu, and their answers are clearer, even citing references.

/

All-encompassing, because the branches of chemistry are very different, so there are many terms in other foreign websites, which are more suitable.

/

Finally, there is a domestic chemical engine, which is famous!

Also, recommend a technical article distribution center.

/home page

Of course, the above information is useful, first of all, foreign languages should be excellent.